Three-dimensional composites of nickel cobalt oxide/ graphene on nickel foam for supercapacitor electrodes, and preparation method thereof

Abstract

Provided is a three-dimensional composite of nickel cobalt oxide/graphene on nickel foam as high-performance electrode materials for supercapacitors and a method for preparing the same, and the electrode comprising a three-dimensional nickel cobalt oxide/graphene on nickel foam exhibited an ultrahigh specific capacitance of 2,260 F/g at a current density of 1 A/g.

What is claimed is: 
     
       1. A method for preparing a three-dimensional composite of nickel cobalt oxide/graphene on nickel foam comprising the steps of:
 (a) forming a graphene oxide thin film by immersing nickel foam in a graphene oxide solution and electrodepositing simultaneously; 
 (b) forming nickel cobalt hydroxide nanoparticles on the top of graphene oxide layer by adding the nickel foam covered with the graphene oxide thin film in an electrolyte solution mixed with bimetallic nickel and cobalt hydroxide and electrodepositing simultaneously; and 
 (c) calcining the nickel foam covered with the graphene oxide thin film and nickel cobalt hydroxide nanoparticles. 
 
     
     
       2. The method for preparing a three-dimensional composite of nickel cobalt oxide/graphene on nickel foam according to  claim 1 , wherein the electrodeposition step (a) is performed at 0.1 to 1 V for 5 to 15 min. 
     
     
       3. The method for preparing a three-dimensional composite of nickel cobalt oxide/graphene on nickel foam according to  claim 1 , wherein electrodeposition step (b) is performed at −1.5 to −0.5 V for 5 to 15 min. 
     
     
       4. The method for preparing a three-dimensional composite of nickel cobalt oxide/graphene on nickel foam according to  claim 1 , wherein the electrolyte comprises nickel nitrate and cobalt nitrate at a molar ratio of 1:3 to 3:1. 
     
     
       5. The method for preparing a three-dimensional composite of nickel cobalt oxide/graphene on nickel foam according to  claim 1 , wherein the calcination step (c) is performed at a temperature of 200 to 350° C. for 1 to 5 h.